Structural-induced antiferromagnetism in Mn-based full Heusler alloys: The case of Ni2MnAl

Abstract

We employ ab initio electronic structure calculations and a model Heisenberg Hamiltonian, and show that the Heusler alloy ${\text{Ni}}_2\text{MnAl}$ exhibits a ferrromagnetic–antiferromagnetic phase transition upon Mn–Al disorder. The transition is triggered by the smaller Mn–Mn nearest-neighbors distance in accordance to the Bethe–Slater curve. Our results explain available experimental data and show that the prevention of disorder is essential to achieve maximum performance in Heusler-based devices.